The purpose of this project is to define the biochemical composition of the major surface constituents, especially the "agglutinogens," of Bordetella pertussis and their relationship to the pathogenicity and epidemiology of whooping cough. Isogenic clones of virulent and avirulent pertussis organisms are compared for differences in SDS-PAGE profiles after extrinsic labeling by 125Iodine. Radio-immune precipitates of solubilized antigen-antibody complexes are used to identify virulent-associated bands which can be further characterized by peptide-mapping. These bands and/or their associated antigens are isolated for raising specific hyperimmune antisera and for screening hybridoma antibody. The specific antibodies so raised are then used for screening chemically-induced mutants altered in production of virulence-associated antigens. Analysis of specific mutants can define the genetics of virulence in B. pertussis for further understanding of pathological and immunological mechanisms of whooping cough.